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Extensive Parametric Studies (extensive + parametric_studies)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

Response simulation and seismic assessment of highway overcrossings

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2010
Anastasios Kotsoglou
Abstract Interaction of bridge structures with the adjacent embankment fills and pile foundations is generally responsible for response modification of the system to strong ground excitations, to a degree that depends on soil compliance, support conditions, and soil mass mobilized in dynamic response. This paper presents a general modeling and assessment procedure specifically targeted for simulation of the dynamic response of short bridges such as highway overcrossings, where the embankment soil,structure interaction is the most prevalent. From previous studies it has been shown that in this type of interaction, seismic displacement demands are magnified in the critical bridge components such as the central piers. This issue is of particular relevance not only in new design but also in the assessment of the existing infrastructure. Among a wide range of issues relevant to soil,structure interaction, typical highway overcrossings that have flexible abutments supported on earth embankments were investigated extensively in the paper. Simulation procedures are proposed for consideration of bridge-embankment interaction effects in practical analysis of these structures for estimation of their seismic performance. Results are extrapolated after extensive parametric studies and are used to extract ready-to-use, general, and parameterized capacity curves for a wide range of possible material properties and geometric characteristics of the bridge-embankment assembly. Using two instrumented highway overpasses as benchmark examples, the capacity curves estimated using the proposed practical procedures are correlated successfully with the results of explicit incremental dynamic analysis, verifying the applicability of the simple tools developed herein, in seismic assessment of existing short bridges. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Seismic interaction in electrical substation equipment connected by non-linear rigid bus conductors

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2007
Junho Song
Abstract An important element within the power transmission lifeline is the electrical substation that typically consists of a complex set of equipment items interconnected through conductor buses or cables. If the connections are not sufficiently flexible, significant dynamic interaction may occur between the connected equipment items during a seismic event, which may result in damage and loss of the equipment. This paper investigates the interaction effect between electrical substation equipment items connected by non-linear rigid bus conductors. The equipment items are modelled as single-degree-of-freedom oscillators by use of appropriate shape functions. The hysteretic behaviours of rigid bus connectors are described by differential equation models fitted to experimental data. An efficient non-linear random vibration method is used to quantify the seismic interaction effect of the connected equipment items. Based on the developed analytical models and method, the effect of interaction in the connected equipment system is investigated through extensive parametric studies. The results lead to practical charts and guidelines for the seismic design of interconnected electrical substation equipment. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Closed-form solution for seismic response of adjacent buildings with linear quadratic Gaussian controllers

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2002
Y. L. Xu
Abstract Closed-form solution for seismic response of adjacent buildings connected by hydraulic actuators with linear quadratic Gaussian (LQG) controllers is presented in this paper. The equations of motion of actively controlled adjacent buildings against earthquake are first established. The complex modal superposition method is then used to determine dynamic characteristics, including modal damping ratio, of actively controlled adjacent buildings. The closed-form solution for seismic response of the system is finally derived in terms of the complex dynamic characteristics, the pseudo-excitation method and the residue theorem. By using the closed-form solution, extensive parametric studies can be carried out for the system of many degrees of freedom. The beneficial parameters of LQG controllers for achieving the maximum response reduction of both buildings using reasonable control forces can be identified. The effectiveness of LQG controllers for this particular application is evaluated in this study. The results show that for the adjacent buildings of different dynamic properties, if the parameters of LQG controllers are selected appropriately, the modal damping ratios of the system can be significantly increased and the seismic responses of both buildings can be considerably reduced. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Model description and parameter extraction of on-chip spiral inductors for MMICs

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2004
W. Y. Yin
Abstract A statistical description of the global performance of on-chip spiral inductors, based on extensive measurement is presented. These inductors were fabricated with different turn numbers or track lengths/track widths, but with the same spacing. From the S parameters measured using a de-embedding technique, the inductance L, Q factor, self-resonance frequency, and figure-of-merit indicator (FMI) of these inductors are determined. Various local scalable formulas are obtained in order to describe the features of these inductors. Based on extensive parametric studies, certain ways to improve these inductor performances can be found. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 111,121, 2004. [source]